This invention relates to cartons, and more particularly to an improved opening flap structure for the side wall of a relatively flat paperboard carton.
Cartons of the hereinabove briefly described type have relatively narrow side walls closed by folded flaps that include means for opening the carton to provide access to its contents. One such closure flap structure is disclosed in my U.S. Pat. No. 4,096,948, issued June 27, 1978, and assigned to the assignee of the present invention. In the referenced closure flap structure, one flap overlies and is adhered to the other. The overlying flap is hingedly joined by a weakened hinge line to a carton wall panel. Tearing the overlying flap is achieved by grasping one end of the flap and pulling it to tear it from the adherent underlying flap and along the weakened hinge line. Tearing from the adhesive is random as between the outer and inner flaps.
Provinding an improved easy opening zipper structure for such a carton has proven difficult, since the flaps have been found to be too narrow for inclusion of a standard double herringbone zipper requiring substantial width. In narrow cartons there is insufficient space on a closure flap to incorporate both the double herringbone structure, i.e., lines of weakness on both sides of the tear strip, and means for effectively sealing the flaps.
It is a general objective of the present invention to provide an easily removable tear strip for opening the relatively narrow side wall of a flat carton.
It is a further objective of the invention to provide a tear strip for a relatively narrow wall of a paperboard container, wherein the strip is removable in predictable controlled manner.